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Quenche Venting

Anybody know of a good resource for quench venting. What i got from the MRI equipment manf was kinda bah. Basically i am interested in the venting material i.e 304 10 gauge round ducting is there any specfics on the contraction joints. The equipment manuf. just shows they need them but no more detail the eng didnt put any info on the drawings except to refer to the manuf. specs. Any help would apperciated

While the risks are greatest when volumes of liquid helium are brought to the magnet to fill the cryostat and replace escaped helium, there is an omnipresent risk of a specific magnet failure, called a quench, when temperature inside the cryostat exceeds the allowable limit and the cryogens boil into a vaporous state, bursting through an escape valve.

The profound thermal expansion of boiling liquid helium is similar to a small explosion, which blasts super-cold vaporous helium from the magnet vessel. Nearly all clinical superconducting magnets have a cryogen vent or quench pipe, which is essentially a chimney intended to duct escaping cryogens to some safe discharge point. From the pressure valve, escaping cryogenic gas is supposed to be ducted to outside the building, frequently an unoccupied rooftop, where it blasts out. However, there have been multiple failures of cryogen vent systems stemming from a variety of sources such as improper design, construction failures, and inadequate maintenance.

If the cryogen vent system fails, hundreds of thousands of liters of gaseous helium can be vented into the magnet room. This super-cold helium, in addition to posing a direct risk of severe cold burns, displaces the oxygen in the room creating an asphyxiation hazard. The expanding cryogenic gas will also pressurize the room. If the door swings into the magnet room, the pressure may prevent opening the door to evacuate any trapped patient or staff member until the pressure is dissipated.